Electronic pressure relief valve for engine oil pump

ABSTRACT

A pressure regulator for an oil pump of a motor vehicle comprises a plunger and a coil. The plunger is normally disposed to cover a flow release chamber, and the coil is energizable to move the plunger to uncover the flow release chamber.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates generally to oil pumps for motor vehicles, and relates more particularly to an electronic pressure relief valve for an engine oil pump.

BACKGROUND OF THE INVENTION

[0002] Oil pumps mounted to an internal combustion engine and directly driven by an end of the engine crankshaft are well known. In particular, gear-type oil pumps are popular in motor vehicles. For example, U.S. Pat. No. 5,085,187 teaches an integral engine oil pump and pressure regulator in which elements of the pump are housed within an internal recess in the engine crankcase. The '187 patent is assigned to the assignee of the present invention, and is hereby incorporated by reference.

[0003] In internal combustion engines, particularly of the type employed in land vehicular propulsion, it has become customary to monitor the pressure of the engine lubrication system, and to inform the engine operator of the monitored pressure or of a reduction in pressure below a predetermined minimum valve. This communication to the operator is, of course, intended to prevent unlubricated engine operation.

SUMMARY OF THE INVENTION

[0004] In accordance with one aspect of the present invention, a pressure regulator is provided for an oil pump of a motor vehicle. The pressure regulator comprises a plunger and a coil. The plunger is normally disposed to cover a flow release chamber, and the coil is energizable to move the plunger to uncover the flow release chamber.

[0005] Accordingly, it is an object of the present invention to provide an apparatus of the type described above that improves the overall performance of an engine oil pump.

[0006] Another object of the present invention is to provide an apparatus of the type described above that improves the oil pressure and flow control performance for cylinder head and other key lubrication locations.

[0007] Another object of the present invention is to provide an apparatus of the type described above that allows for the use of relatively large head gasket orifice sizes.

[0008] Another object of the present invention is to provide an apparatus of the type described above that improves aeration, resulting in improved lubrication, improved hydraulic lifter operation and reduction of power losses.

[0009] These and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a cross-sectional view of an oil pump and pressure regulator according to the present invention for an internal combustion engine of a motor vehicle; and

[0011]FIG. 2 is another cross-sectional view of the oil pump and pressure regulator with a plunger in a fully open position.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0012]FIG. 1 shows one embodiment of an oil pump and pressure regulator according to the present invention for a motor vehicle. An end portion 12 of a crankshaft of an internal combustion engine of the vehicle extends into an oil pump housing 10. As is well known, the crankshaft is secured for rotation in an engine block, and the extreme end of the end portion 12 of the crankshaft projects externally from the oil pump housing 10. This permits a pulley or the like to be attached to the engine crankshaft for driving engine accessories through a belt.

[0013] An inlet passage 36 in the housing 10 is adapted to be connected to an oil pickup means (not shown) to transmit oil from the interior or oil reservoir of the engine. An outlet passage 40 in the housing 10 likewise is adapted to connect to the lubricating system of the engine. The oil pump includes an inner gear pump element 42 encircled by an outer gear pump element 44. The inner element 42 has a central aperture 46 through which the end portion 12 of the crankshaft extends, and a plurality of axially extending channels or keyways 48 formed in the aperture 46. When the inner element is assembled to the end portion 12 of the crankshaft, the keyways 48 are aligned with corresponding projections 50 formed on the end portion 12 of the crankshaft to effectively secure the inner element 42 together for rotation with the crankshaft.

[0014] The outer peripheral edge of the inner oil pump element 42 has a contour or configuration including lobes 54 evenly spaced around its circumference. The lobes 54 extend radially outwardly, and are connected by inwardly curved connecting surfaces 56. The inner edge configuration of the central opening in the outer oil pump element 44 also has a contoured edge which is complimentary to the outer edge of the inner element. This inner edge is configured with evenly spaced pockets 58 and with curved surfaces 60 extending therebetween. The pockets 58 are complimentary to the lobes 54, and the curved surfaces 56 are complimentary to the curved surfaces 60. The illustrated embodiment of the oil pump includes ten lobes 54 on the inner element 42 and eleven pockets 58 in the outer element 44. Because the outer element has one more pocket than the number of lobes on the inner element, one complete rotation of the inner element 42 by the crankshaft causes the outer element 44 to rotate about 0.909 (10/11th) of a complete rotation.

[0015] The view of the gear pump in FIG. 1 is from the interior of the engine. Therefore, the usually standard clockwise rotation of vehicle engines (viewed head on toward the front exterior) would be indicated by a counterclockwise rotation of the elements 42 and 44. A space 64 between the elements 42 and 44 expands in volume as the shaft 12 rotates counterclockwise. This space overlies an inlet opening of the inlet passage 36, and oil is drawn into the space therethrough. The expansion of the spaces is evident by noting the next space 66 advancing counterclockwise. In the counterclockwise direction, the spaces contract or become progressively smaller. Oil is discharged from these spaces into the outlet passage 40.

[0016] During operation of the engine and its oil pump, oil pressure generated adjacent an outlet opening into the outlet passage 40 is normally below a prescribed pressure level for which the engine and pump are designed. However, if the oil pressure level at the outlet is above the prescribed design level, an electronic pressure relief valve 70 operates.

[0017]FIG. 2 shows the electronic pressure relief valve 70 in greater detail. The electronic pressure relief valve 70 includes a coil 72, a spring 74, and a plunger 76. In a preferred embodiment, an electronic control unit (ECU) 78 monitors vehicle parameters such as engine speed, oil temperature, manifold absolute pressure, air flow, and throttle position in order to estimate the oil pressure developed by the oil pump. It should be understood, of course, that rather than such an open loop configuration, a dedicated oil pressure sensor can be placed somewhere in the oil circuit.

[0018] If the ECU 78 determines that pressure at the oil pump outlet is too high, the ECU energizes the coil 72 to retract the plunger 76 against the bias of the spring 74 to any partially open or fully open position. In the fully open position shown in FIG. 2, a larger diameter base portion of the plunger 76 has retracted from a position covering a flow release chamber 80. As mentioned, the plunger can be retracted to only partially uncover the flow release chamber 80. The flow release chamber 80 is in fluid communication with a high pressure port or chamber 82 such that the oil pressure decreases in the pump high pressure chamber, which correspondingly reduces the oil pressure and flow at the pump outlet port.

[0019] Because the oil pressure relief valve of the present invention is controlled by the ECU as a function of parameters such as engine speed, oil temperature, and throttle body position, the output of the pump is optimized and pressure/flow are well controlled at multi-operation points. While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein. 

1. A pressure regulator for an oil pump of a motor vehicle, the pressure regulator comprising: a plunger normally disposed to cover a flow release chamber; and a coil energizable to move the plunger to at least partially uncover the flow release chamber.
 2. The pressure regulator of claim 1 further comprising a spring disposed between the plunger and the coil.
 3. The pressure regulator of claim 2 wherein the spring normally biases the plunger to cover the flow release chamber.
 4. The pressure regulator of claim 1 further comprising an electronic control unit in communication with the coil.
 5. The pressure regulator of claim 4 wherein the electronic control unit controls the coil as a function of engine speed.
 6. The pressure regulator of claim 4 wherein the electronic control unit controls the coil as a function of oil temperature.
 7. The pressure regulator of claim 4 wherein the electronic control unit controls the coil as a function of throttle position.
 8. An oil pump for a motor vehicle, the oil pump comprising: an inner gear; an outer gear engaged with the inner gear to pump oil to a flow release chamber; a plunger normally disposed to cover the flow release chamber; and a coil energizable to move the plunger to at least partially uncover the flow release chamber.
 9. The oil pump of claim 8 further comprising a spring disposed between the plunger and the coil.
 10. The oil pump of claim 9 wherein the spring normally biases the plunger to cover the flow release chamber.
 11. The oil pump of claim 8 further comprising an electronic control unit in communication with the coil.
 12. The oil pump of claim 11 wherein the electronic control unit controls the coil as a function of engine speed.
 13. The oil pump of claim 11 wherein the electronic control unit controls the coil as a function of oil temperature.
 14. The oil pump of claim 11 wherein the electronic control unit controls the coil as a function of throttle position.
 15. An oil pump having a flow release chamber, the oil pump comprising: a plunger normally disposed to cover the flow release chamber; a coil energizable to move the plunger to at least partially uncover the flow release chamber; and an electronic control unit in communication with the coil.
 16. The oil pump of claim 15 further comprising a spring disposed between the plunger and the coil.
 17. The oil pump of claim 16 wherein the spring normally biases the plunger to cover the flow release chamber.
 18. The oil pump of claim 15 wherein the electronic control unit controls the coil as a function of engine speed.
 19. The oil pump of claim 15 wherein the electronic control unit controls the coil as a function of oil temperature.
 20. The oil pump of claim 15 wherein the electronic control unit controls the coil as a function of throttle position. 